<StructureDefinition xmlns="http://hl7.org/fhir" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://hl7.org/fhir ../../publish/fhir-single.xsd">
  <id value="questionnaire-unit" />
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-wg">
    <valueCode value="fhir" />
  </extension>
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-fmm">
    <valueInteger value="1" />
  </extension>
  <url value="http://hl7.org/fhir/StructureDefinition/questionnaire-unit" />
  <version value="4.6.0" />
  <name value="unit" />
  <status value="draft" />
  <date value="2013-07-04" />
  <publisher value="HL7" />
  <contact>
    <telecom>
      <system value="url" />
      <value value="http://www.hl7.org" />
    </telecom>
  </contact>
  <description value="Provides a computable unit of measure associated with numeric questions to support subsequent computation on responses. This is for use on items of type integer and decimal, and its purpose is to support converting the integer or decimal answer into a Quantity when extracting the data into a resource.      If a 'display' value is provided for valueCoding of this extension and the associated question item does not have a child 'display' item with an itemControl extension of 'unit', then form fillers SHOULD take the display value of this extension and use it as as the unit display." />
  <fhirVersion value="4.6.0" />
  <mapping>
    <identity value="rim" />
    <uri value="http://hl7.org/v3" />
    <name value="RIM Mapping" />
  </mapping>
  <kind value="complex-type" />
  <abstract value="false" />
  <context>
    <type value="element" />
    <expression value="Questionnaire.item" />
  </context>
  <contextInvariant value="type='integer' or type='decimal'" />
  <type value="Extension" />
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/Extension" />
  <derivation value="constraint" />
  <differential>
    <element id="Extension">
      <path value="Extension" />
      <short value="Unit for numeric answer" />
      <definition value="Provides a computable unit of measure associated with numeric questions to support subsequent computation on responses. This is for use on items of type integer and decimal, and it's purpose is to support converting the integer or decimal answer into a Quantity when extracting the data into a resource." />
      <comment value="The human-readable unit is conveyed as a display element.  This element is for computation purposes." />
      <min value="0" />
      <max value="1" />
      <mapping>
        <identity value="rim" />
        <map value="N/A (MIF-level)" />
      </mapping>
    </element>
    <element id="Extension.extension">
      <path value="Extension.extension" />
      <max value="0" />
    </element>
    <element id="Extension.url">
      <path value="Extension.url" />
      <fixedUri value="http://hl7.org/fhir/StructureDefinition/questionnaire-unit" />
    </element>
    <element id="Extension.value[x]">
      <path value="Extension.value[x]" />
      <min value="1" />
      <type>
        <code value="Coding" />
      </type>
    </element>
  </differential>
</StructureDefinition>